Generator ignition control



Oct. 10, 1933. c. RINGWALD 2 GENERATOR IGNITION CONTROL Filed Sept. 26,1931 2 SheefcS- Sheet 1 //7 V/Y Zar Clare/2C6 Ring wa /a y 2f My Affmneys Patented Oct. 10, 1933 UNITED STATES PATENT OFFICE one-half to John A. Dienner, Evanston, 11!

Application September 26, 1931 Serial No. 565,287

10 Claims. (Cl. 123148) My invention relates in general to electrical generators, and in particular to electrical generators driven by internal combustion engines. It is particularly adapted to generators used in automobiles.

A primary purpose of my invention is to provide in such a generator a definite control of the current regulation so as to cause the generator to deliver either a constant current at all speeds or a current varying slightly with engine speed as may be desired. This is especially desirable in cars having the free wheeling feature, where the engine may idle a considerable portion of the driving time.

A further object of my invention is to employ the breaker and induction coil of the ignition system for this purpose.

In the preferred embodiment of my invention, I connect the generator field winding and the primary of the spark coil within a common circuit, and adjust the circuit in order to accomplish the purpose of my invention. I thereby adapt the inductive properties of the ignition circuits to the control of the generator and make the mag-- netic energy of the generator field structure available for use in the ignition system.

My method of generator regulation provides the assurance that the generator will deliver current at substantially all engine speeds, thus greatly reducing the possibility of exhausting the storage battery. A substantially constant current at all speeds permits the use of a comparatively low current and a small size generator.

of particular importance is the fact that my invention provides a substantial current delivery from the generator at the idling speed of the engine, for in a car having the free wheeling feature, the engine may idle a considerable portion of the driving time. In this respect, my invention ofiers a decided advantage over the popular third brush" method of regulation.

A further advantage lies in the construction of the ignition coil. In the preferred embodiment of my invention, I connect the primary of the ignition coil in series with the generator field winding. The primary winding so connected'takes a much greater current than as ordinarily used in an automobile, and so may be wound with a much larger size wire and fewer coil turns, thus effecting an appreciable saving in manufacturing cost.

The ignition system of an internal combustion engine requires of the spark coil both a high voltage to break down the gas insulation between the electrodes of the spark plug, and suflicient energy to ignite the gas. To obtain the high initial voltage, spark coils are made with considerable air in the magnetic circuit so as to permit a rapid change of fiux. But such a loose magnetic circuit can contain only a small amount 50 of energy so that under certainadverse conditions, such as may be presented by a cold engine, or an improper fuel mixture, the spark is too weak to ignite the gas. My invention imposes on the induction coil the comparatively slow kick of 55 the generator field circuit to supplement that of the spark coil itself, so as to supply a high energy, follow-up discharge to the spark plug electrodes.

In order to acquaint those skilled in the art with the construction and practice of my invention, I 7 shall now describe its preferred embodiment and method of operation, reference being had to the accompanying drawings which form a part of this specification.

In the drawings:

Figure 1 illustrates in diagram the preferred embodiment of my invention;

Figures 2, 3, 4 and 5 are diagrams illustrating a few circuit modifications presenting certain operating characteristics different from those of Figure 1; and

Figures 6 and '7 are curves included for descriptive purposes.

The circuit of Figure 1 consists of a storage battery 1, a generator having an armature 2 and g5 field windings 4 and 5 with a condenser 10 shunt-- ing winding 5, a cut-out device 3, and ignition spark coil having a primary winding 6 and a secondary winding 7, breaker points 8 shunted by condenser 9, and a distributor head 11. The breaker consists of an arm 13 actuated by a cam 14, and a contact screw 12 which provides the breaker gap adjustment. The generator is preferably driven from )he engine crank shaft as is the usual practice. Likewise the breaker cam 14 and distributor 11 are operated as is the usual practice in synchronism with the engine crank shaft.

During normal operation of the engine, the breaker points 8 being gear driven from the en- 10o gine crankshaft not shown periodically open and close, and thereby periodically interrupt the circuit through field winding 5 of the generator and primary winding 6 of the induction coil. These periodic interruptions effect a reduction of the mean value of the current through this circuit. Furthermore, this reduction of the mean value of the current becomes greater as the frequency of the interruption becomes greater, that is, as the speed of the engine increases. Thus the increase of the generator armature speed which is incident to an increase of the engine speed, is compensated for by a decrease in the field excitation, so as to leave the current output of the generator substantially unchanged or only slightly varied.

With the breaker points 8 open, the circuit through the field winding 5 and the induction coil winding 6 is completed through the condenser 9, thus supplying a path for the transient current which tends to maintain the generator field during the time that the breaker points are open, and which also serves to transfer to the spark coil the energy released by the partial collapse of the generator field. To this end, a condenser 10 shunting the main field winding 5 may sometimes be desirable.

On the opening of the breaker points 8 current oscillations are set up in the circuit consisting of the windings 5 and 6 and the condensers 9 and 10. But winding 6 is coupled to winding 7 which is in a circuit containing a high resistance, namely the spark gap 17. The spark gap will therefore damp out these current oscillations by taking their energy from them.

The auxiliary shunt field winding 4 shown in Figure 1 is not a necessary part of my invention, but is included as an optional feature. The use of this auxiliary field provides a base excitation on which that of the main winding 5 is superimposed. The two field windings may of course be arranged either magnetically aiding or. opposing. Butwinding4willalsoactasadampingcircuit to prevent rapid changes of the field flux and in so doing will consume energy that would otherwise be available for use by the ignition system.

Figure 2 illustrates a modification of the circuitofFigure1inthatthewindings5and6are connected in parallel rather than in series. This alters somewhat the inductive effects imposed on the generator field by the induction coil, and presents a simple method of utilizing the energy of the generator field in the operation of the ignition system, since the inductive kick of the .field circuit is imposed directly across the terminals of the primary winding of the spark coil.

In Figure 3 the main field winding of the generator has been divided into two parts 5a and 5b, and the induction coil 6 is shunted across 5a.

A special feature of my invention is a provision for varying the speed current characteristic of the generator by means of one or more simple adjustments. In this I efiect a change from a characteristic such as b in Figure 7 to some other characteristic such as a or c. This is most easily accomplished by varying the setting of the breaker points by means of screw 12 shown in Figure 1. Since screw 12 actsas a stop for arm 13, such an adjustment varies the arc of contact of cam 14 against the lever 13 and thereby varies the time of duration of the open condition of the breaker points relative to the time of duration of the clomd condition.

This or other adjustments of the circuit effect a change in the pattern of the periodic variations of current in the field circuit of the generator, and thereby alter the conditions of the controlso as to obtain a slightly diiferent characteristic. A method offering possibilities for a large number of adjusted conditions is shown in,Figure 4. This method employs an additional breaker 8b operating in adjustable time relation to the main breaker 8a. The setting of each breaker is also independently adjustable. The time relation adjustment may be accomplished by means of a rotatable mounting for one of the breakers similar to the spark adjustment of an automobile.

Figure 5 illustrates a possible means of adjusting the inductive effects by the use of a resistor 15 in the condenser branch.

Figures 6 and '7 illustrate graphically the unique superiority of my invention over the third-brush method of regulation. The curve of Figure 6 shows the approximate speed current characteristic of the conventional third brush generator, in which m is the idling speed of the engine. Note that the generator delivers little or no current at the idling speed of the engine. The curve of Figure '7 represents similarly the speed current characteristic of a generator using my invention. Note that a substantial current may be delivered at all engine speeds.

While I have shown and described a circuit according to my invention employing the shunt 05 field of the generator, I do not intend to limit myself to this one embodiment, inasmuch as the invention may be embodied in forms employing other known or conventional types of field winding arrangements, including the field of the third brush generator.

I do not intend to be limited to the details shown or described except as they are recited in the appended claims.

I claim:

1. In an electrical apparatus of the class described, a generator having a field winding, an induction coil electrically connected with said field winding, and means for periodically interrupting the circuit containing said field winding and induction coil to eifect the control of the output of said generator.

2. In an electrical apparatus of the class described, a generator having a field winding, an induction coil electrically connected with said field winding, and an ignition timer arranged to interrupt the current through said field winding, whereby to control the current delivered by said generator at various rotative speeds of said generator. p

3. In an electrical apparatus of the class described, a generator having a field winding, an induction coil electrically connected with said field winding, means for periodically interrupting the circuit containing said field winding and induction coil, and means for varying the. pattern of the periodic interruption of said .circuit, whereby to eifect the control of the out-v put of said generator.

4. In an electrical apparatus of the class described, a generator having a field winding. an, induction coil electrically connected to said field winding, means for periodically interrupting the circuit containing saidfield winding and induction coil, and means for varying the frequency of said periodic interruption whereby to control the output of said generator at its various rotative speeds.

5. The method of controlling the fiow of current from a. generator which consists in super- 14o imposing intermittent inductive elects upon the field of the generator so as to maintain said current at a predetermined value during various rotative speeds of said generator.

6. The method of regulating the output of a generator by intermittently interrupting its field circuit and imposing inductive efiects on its field winding.

'7. The method of regulating the output of a generator by periodically interrupting its field circuit and by varying the pattern of the periodic interruption to eflect a variation of the regula- ,tion characteristic of the generator.

8. The method of regulating the output of a generator by imposing periodic inductive effects on its field winding and varying the pattern of said periodic inductive eflects.

9. The method of regulating the output of a generator by periodically interrupting its field 

